In transit refrigeration heat transfer apparatus

ABSTRACT

An apparatus for providing heat transfer to a compartment includes a housing having a chamber therein for receiving dry ice and a first surface area exposable to a first space in the compartment for heat transfer; and a first assembly moveable with respect to the first surface area for covering a select portion of the first surface area to control heat transfer at the first space. The first assembly includes at least one pivotable louver.

BACKGROUND

The present inventive embodiments relate to apparatus and methods to provide heat transfer for refrigeration of products, such as food products for example, that are in transit.

In transit refrigeration (ITR) and temperature control inside refrigerated transport trucks or containers can be difficult to regulate. Temperature control of such systems, such as for example a carbon dioxide (CO₂) system, is desired for increasing the overall efficiency of the system process, as well as making such system suitable for daily product delivery services. A temperature control system enables chilled and frozen products to be transported effectively and efficiently.

It would therefore be desirable to have an ITR apparatus which can regulate and control refrigeration at a single compartment and at a plurality of compartments concurrently depending upon the temperature demands for each compartment.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present embodiments, reference may be had to the following drawing figures taken in conjunction with the description of the embodiments, of which:

FIG. 1 shows a perspective view of a heat transfer apparatus embodiment according to the invention;

FIG. 2 shows a top plan view along line 2-2 of the embodiment in FIG. 1; and

FIG. 3 shows another embodiment of the heat transfer apparatus according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a heat transfer apparatus embodiment is shown generally at 10. The apparatus includes a container 12 or bunker, wherein five (5) of the side walls 14 of the container 12 are insulated, while a sixth (6^(th)) one of the side walls is not insulated and is constructed as a heat transfer side wall 16 of the container. The side walls 14,16 provide for a space 18 in the container 12. CO₂ snow or dry ice 20 is provided in the space 18. The container 12 is shown having a rectangular shape by way of example only, hence the number of side walls 14 that would be provided for such a structure. The apparatus 10 may be used for in transit refrigeration (ITR) of products such as food products for example.

At least one louver 22, door or slat, and for many applications a plurality of louvers, are mounted to the container 12 for pivotal movement with respect thereto. Each one of the louvers 22 is pivotally connected to the container 12 or the heat transfer side wall 16 by mechanical pivoting fasteners 24 such as for example hinges or pins. The pivoting fasteners 24 permit each one of the louvers 22 to rotate through at least 90 degrees with respect to the surface of the heat transfer side wall 16 for a purpose to be discussed hereinafter.

As shown in particular in FIG. 2, each of the louvers 22 may be provided with insulation 26 along a surface thereof or alternatively, the entire louver 22 may be insulated. Insulation can take the form of any known insulation material available. A length of each one of the louvers 22 is such that when all of the louvers mounted to the heat transfer side wall 16 are folded or pivoted to be in contact with said side wall 16, the louvers 22 provide an insulated surface similar to that provided by the insulated side walls 14. Therefore, the louvers 22 positioned at 28 do not provide heat transfer at the side wall 16. Such an arrangement is shown in FIG. 2, where certain of the louvers 22 as indicated generally at 28 have been folded downward to be parallel with and cover the heat transfer side wall 16, while others of the louvers 22 shown generally at 30 remain in an upright opened or deployed position with respect to the side wall 16. The positioning of the louvers 22 at 30 provides for an increased heat transfer at the side wall 16. Each of the louvers 22 can be positioned separately from other ones of the louvers.

Referring to FIG. 1, the plurality of pivoting louvers 22 enable a select surface area of the heat transfer side wall 16 to be exposed to convection currents 32 in a space or compartment 34. All of the louvers 22 may be in the open or upright position 30, in the closed or seated position 28, or alternatively be arranged in any combination between the positions 28,30.

The air flow 32 may be the result of convection currents in the space 34. The degree of cooling in the space 34 can be controlled by opening and closing the louvers 22 to expose a select amount of the surface area of the heat transfer side wall 16. With all of the louvers 22 in the closed position 28, the heat transfer side wall 16 is completely insulated and therefore minimal, if any, heat transfer effect will occur with respect to the air flow 32. However, with all of the louvers 22 in the open position as shown generally at 30 in FIG. 2, the heat transfer side wall 16 is completely exposed to the air flow 32, thereby providing for a maximum amount of heat transfer to occur to the air flow. Any degree of exposure of the air flow 32 to the heat transfer side wall 16 can be achieved by pivoting the louvers through a 90 degree path of rotation to provide the necessary amount of freezing or chilling of the space 34 by the air flow 32.

The embodiment shown in FIG. 1 can be mounted to a side wall or roof of an ITR vehicle (not shown). If the apparatus 10 is mounted to the roof (not shown) for example, the louvers 22 when pivoted to the open position 30 will extend or point downward into the space 34 of the vehicle.

The CO₂ snow 20 loaded into the space 18 from an inlet port 36 of the container 12 can be in pellet form or as snow particles generated from a CO₂ snow horn (not shown). Sensors (not shown) for sensing temperature of the space 34 can also be provided to generate a signal of the temperature of the space and communicate same to a control apparatus (not shown) to adjust opening and closing of the louvers 22 to provide the right amount of heat transfer effect to the air flow 32.

FIG. 3 shows another embodiment 40 of the ITR heat transfer apparatus. The apparatus 40 is constructed for use with a plurality of spaces 42,44 of a compartment 46, wherein each one of the spaces may require a different temperature of cooling, i.e. for example the space 42 may be required for freezing products, while the space 44 may be required for keeping products only chilled or cooled.

The apparatus 40 includes a container 48 having a side wall 50 defining a chamber 52 therein. The container 48 is provided with insulation 54 at four of the six sides of the side wall 50. An inlet port 56 is provided to introduce CO₂ snow 58 into the chamber 52.

The side wall 50 has opposed side wall portions 60,62. The side wall portions 60,62 are not insulated and therefore provide for the maximum heat transfer effect in view of their contact and exposure to the CO₂ snow 58. It can be seen from FIG. 3 that the chamber 52 in which the CO₂ snow 58 is disposed can also be constructed with a wall 64 which segregates the chamber 52 into a pair of chambers 58A,58B for a purpose to be described hereinafter. As shown in FIG. 3, the chamber portion 58A is exposed to the side wall portion 60, while the chamber portion 58B is exposed to the side wall portion 62. In such a construction, the inlet port 56 would be disposed for access to both chamber portions 58A,58B so that introduction of the CO₂ snow 58 can be with respect to both chamber portions.

The uninsulated side portions 60,62 each have at least one and for most applications a plurality of moveable louvers 66,68 mounted thereto for pivoting movement with respect to each one of the respected side portions. In the embodiment of FIG. 3, the louvers 66 are mounted for pivoting movement with respect to the side wall portion 60 of the container 48 facing the space 42 where products are to be frozen. The louvers 68 are mounted for pivoting movement with respect to the side wall portion 62 of the container 48 facing the space 44 where products are to be chilled. The louvers 66,68 can be attached by mechanical fasteners (not shown) similar to that which were used in the embodiment shown in FIGS. 1 and 2, such as for example mechanical hinges. The louvers 66,68 have a construction similar to that of the louvers 22 of the embodiment in FIGS. 1 and 2, i.e. the louvers 66,68 may be provided with insulation along a surface which is exposed to the space 42 or space 44, respectively, or the louvers 66,68 may be entirely insulated.

The heat transfer apparatus 40 functions in a manner similar to that with respect to the embodiment of FIGS. 1 and 2, except that the apparatus 40 can provide heat transfer to air flow 70 in the space 42 for frozen products, and also heat transfer to the air flow 72 in the space 44 for chilled products.

Since the space 42 is for frozen products, the maximum heat transfer effect will probably be necessary with respect to the CO₂ snow 58. Therefore, a majority, if not all, of the louvers 66 are in the upright or completely open position to thereby expose the uninsulated side wall portion 60 to the air flow 70 for maximum heat transfer to be caused by the CO₂ snow 58. For the space 44 however, only certain of the louvers 68 are in the open position because the amount of heat transfer necessary for the space 44 is not as great as is required for the space 42. Therefore, certain of the louvers 68 are in the closed position lying against the side wall portion 62, or are partially pivoted shut to prevent or limit heat transfer for the space 44. In operation, one or a plurality of the louvers 68 may be closed or disposed in various angled positions commensurate to that which must occur between the air flow 72 and the side portion 62 to provide the necessary heat transfer for the space 44.

The air flows 70,72 are essentially warmer air, i.e. warm air rises in the compartment 46. As the air flows 70,72 are exposed to the corresponding ones of the side wall portions 60,62 for heat transfer, the air flows cool and sink between corresponding ones of the louvers 66,68 as they proceed downward along the side wall portions 60,62, whereupon airflow 74 is at a reduced temperature in the space 42, while air flow 76 is also at a reduced temperature in the space 44.

Sensors 78,80 are mounted to be in communication with the spaces 42,44, respectively, to sense freezing and chilling temperatures in the compartment 46. The sensors 78,80 can be connected, wirelessly or otherwise, to a controller (not shown) to receive signals from the sensors to thereby adjust the louvers 66,68 to the required positions for heat transfer necessary at the spaces 42,44. The sensors 78,80 can also be used with the embodiment of FIG. 1.

CO₂ snow 58 will be consumed and therefore sublime in different degrees, depending upon its exposure to one of the side wall portions 60,62. For example, the CO₂ snow 58 in the chamber portion 58A which is closer to the side wall portion 60 will become more quickly reduced because the demand for heat transfer is increased in the frozen space 42 due to all of the louvers 66 being in the open or deployed position. In contrast, a level of the CO₂ snow 58 in the chamber portion 58B which is closer to the side wall portion 62 will not sublime as quickly because certain of the louvers 68 are closed, thereby reducing the heat transfer effect and the related demand on use of the CO₂ snow, as the space 44 is only for chilling, as opposed to freezing. The independent movement of the louvers 66,68 provides for versatile temperature control to regulate spaces in an ITR container, truck, barge, etc.

It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the invention may be combined to provide the desired result. 

1. An apparatus for providing heat transfer to a compartment, comprising: a housing having a chamber therein for receiving dry ice and a first surface area exposable to a first space in the compartment for heat transfer; and a first assembly moveable with respect to the first surface area for covering a select portion of the first surface area to control heat transfer at the first space.
 2. The apparatus of claim 1, wherein the first assembly comprises at least one louver.
 3. The apparatus of claim 2, wherein the at least one louver is insulated.
 4. The apparatus of claim 1, wherein the first assembly is pivotably mounted to the housing.
 5. The apparatus of claim 1, wherein the first assembly comprises a first plurality of louvers, each one of said louvers being independently movable with respect to the first surface area and others of the first plurality of louvers.
 6. The apparatus of claim 1, further comprising an inlet at the housing in communication with the chamber for providing the dry ice to the chamber.
 7. The apparatus of claim 1, further comprising a sensor exposed to sense a temperature of the first space for generating a signal to control movement of the first assembly.
 8. The apparatus of claim 1, wherein the housing further comprises: a second surface area exposable to a second space of the compartment for other heat transfer; and a second assembly movable with respect to the second surface area for covering a select portion of the second surface area to control heat transfer at the second space.
 9. The apparatus of claim 8, wherein the second assembly comprises at least one louver.
 10. The apparatus of claim 9, wherein the at least one louver is insulated.
 11. The apparatus of claim 8, wherein the chamber comprises a first section for receiving the dry ice adjacent the first surface area, and a second section for receiving the dry ice adjacent the second surface area.
 12. The apparatus of claim 8, wherein the second assembly is pivotably mounted to the housing.
 13. The apparatus of claim 8, wherein the second assembly comprises a second plurality of louvers, each one of said louvers being independently movable with respect to the second surface area and others of the second plurality of louvers.
 14. The apparatus of claim 8, further comprising a first sensor exposed to sense a temperature of the first space for generating a first signal to control movement of the first assembly, and a second sensor exposed to sense a temperature of the second space for generating a second signal to control movement of the second assembly. 